Paper Details

Abstract

Pollen grains with compound apertures and possessing one type of endoapertures per colpus are of common occurrence in Angiosperms, whereas those with multiple endoapertures are rather infrequent. Multiple endoapertures per colpus may be with regular discrete shapes or as irregular more flexible ruptures in the endoaperture areas, representing different mechanisms in which harmomegathy function. A total of 19 flowering plant families belonging to 12 Orders are revealed to have representatives with multiple endoapertures, corresponding to about 4.5% of the families and about 19% of the Orders of Eudicots. Synoptic pollen morphological features of these families are investigated, the diversity of endoaperture configuration are traced and possible causes are outlined. Pollen grains with regular discrete endoapertures are dominant over those with irregular ruptures. The latter type, is encountered in the Order Lamiales with the exception of the family Scrophulariaceae and only in the family Resedaceae (Brassicales). The taxonomic significance of multiple endoapertures are outlined, and the distinctive attributes that corroborate with pollen morphological characteristics are defined. It is hoped that this study will stimulate further studies in both types of endoapertures in developing and mature stages to trace their selective advantages and evolutionary pathways.

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